Capacitive touch panel

• US 8,525,811 B2
• Filed: 02/08/2010
• Issued: 09/03/2013
• Est. Priority Date: 01/06/2010
• Status: Active Grant

• Current Assignee: Superc-Touch Corporation
• Original Assignee: Superc-Touch Corporation
• Inventors: Lee, Hsiang-Yu
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): PARKER, JEFFREY ALAN
• Application Number:
  US12/701,611
• Publication Number:
  US 20110163993A1
• Time in Patent Office: 1,303 Days
• Field of Search: 345/156, 345/173, 345/174
• US Class Current: 345/174
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A capacitive touch panel consists of a touch panel having a plural conductive wires, a multiplex selector electrically connected to the plural conductive wires of the touch panel, a first switch electrically connected to the multiplex selector, a first resistor having a first resistor value, a second switch electrically connected to the resistor and the first switch, a capacitor having a capacitance value, the capacitor electrically connected to the first switch and the second switch, a third switch electrically connected to the capacitor, an Analogue to Digital converter, a fourth switch electrically connected to the Analogue to Digital converter and the third switch, and an integrating circuit electrically connected to the second switch and the fourth switch.

Claims

1. A capacitive touch panel device comprising:

a touch panel having a plural conductive wires;

a multiplex selector electrically connected to the plural conductive wires of the touch panel;

a first switch electrically connected to the multiplex selector;

a first resistor having a first resistor value;

a second switch electrically connected to the first resistor and the first switch;

a capacitor having a capacitor value;

the capacitor electrically connected to the first switch and the second switch;

a third switch electrically connected to the capacitor;

an analog to digital converter;

a fourth switch electrically connected to the analog to digital converter and the third switch; and

an integrating circuit electrically connected to the second switch and the fourth switch,

wherein the third switch is switched to a DC power source and the second switch is switched to the capacitor for charging the capacitor;

there is a conductive resistor with a second resistor value existed in the conductive wires between the contacting point of the touch panel and the multiplex selector;

the third switch is switched to the fourth switch so to make the analog to digital converter electrically connect to the capacitor to read a first voltage value after the capacitor is charged;

the first switch is switched to the capacitor so to make the capacitor charge a floating capacitor which is induced by an object applied to a contacting point on the touch panel; and

the integrating circuit records an absolute value of a current flowing through the first resistor.

2. The capacitive touch panel as claimed in claim 1, wherein the first switch is switched to the second switch so to discharge the floating capacitor and the integrating circuit records the absolute a value of the current flowing through the first resistor.

3. The capacitive touch panel as claimed in claim 2, wherein the first switch and second switch again are switched to the capacitor so that the capacitor charge the floating capacitor applied to the contacting point;

and the integrating circuit records an absolute value of a current flowing through the first resistor; and

the first switch is switched to the second switch again so to discharge the floating capacitor applied to the contacting point and the integrating circuit records the absolute value of a current flowing through the first resistor.

4. The capacitive touch panel as claimed in claim 3, wherein the integrating circuit stops to record the absolute value of a current flowing through the first resistor;

and the second switch is switched to the capacitor and the analog to digital converter reads a second voltage value of the capacitor.

5. The capacitive touch panel as claimed in claim 4, wherein the fourth switch is switched to the integrating circuit so to make the analog to digital converter read a total value of current of the equivalent current of the first resistor.

6. The capacitive touch panel as claimed in claim 5, wherein the analog to digital converter transmits the first voltage value, the second voltage value and the value of current to a device driver in order to calculate a second resistor value of such conductive resistor.

7. The capacitive touch panel as claimed in claim 6, wherein the value of the second resistor is calculated as:

8. The capacitive touch panel as claimed in claim 7, wherein the second resistor value is converted into a coordinate value of a contacting point by a device driver, and if I is smaller than a preset value, it means no touching on the touch panel.

9. The capacitive touch panel as claimed in claim 1, wherein there is an inductor electrically connected between the first switch and the second switch.

10. The capacitive touch panel as claimed in claim 1, wherein the multiplex selector is used to scan the plural conductive wires of the touch panel sequentially.

11. A capacitive touch panel comprising:

a touch panel having a conductive plane and plural detecting points;

a multiplex selector electrically connected to the plural detecting points of the touch panel;

a first switch electrically connected to the above multiplex selector;

a first resistor having a first resistance value;

a second switch electrically connected to the first resistor and the first switch;

a capacitor having a capacitance value, the capacitor electrically connected to the above first switch and the second switch;

a third switch electrically connected to the capacitor;

an analog to digital converter;

a fourth switch electrically connected to the analog to digital converter and the third switch; and

an integrating circuit electrically connected to the second switch and the fourth switch,

wherein the third switch is switched to a DC power source and the switch is switched to such capacitor for charging such capacitor;

the touching point and the conductive plane of plural detecting points, there is a conductive resistor existed individually between each detecting point and the touching point;

there the conductive resistors have an individual resistance value;

the third switch is switched to the fourth switch so to make the analog to digital converter electrically connect to the capacitor to read a first voltage value after the capacitor is charged;

the first switch is switched to the capacitor so to make the capacitor charge a floating capacitor applied to a contacting point on the touch panel; and

the integrating circuit records an absolute value of a current flowing through the first resistor.

12. The capacitive touch panel as claimed in claim 11, wherein the first switch is switched to the second switch so to discharge the floating capacitor;

and the integrating circuit records the absolute value of a current flowing through the first resistor.

13. The capacitive touch panel as claimed in claim 12, wherein the first switch and the second switch again are switched to the capacitor so to make the capacitor charge the floating capacitor applied to the contacting point;

and the integrating circuit records an absolute value of a current flowing through the first resistor; and

again the first switch is switched to the second switch so to discharge the floating capacitor and the integrating circuit records the absolute value of a current flowing through the first resistor.

14. The capacitive touch panel as claimed in claim 13, wherein the integrating circuit stops to record such value of the current flowing through the first resistor;

and the second switch is switched to the capacitor;

the analog to digital converter reads a second voltage value of the capacitor.

15. The capacitive touch panel as claimed in claim 14, wherein the fourth switch is switched to the integrating circuit so to make the analog to digital converter read a total value of current of the equivalent current of the first resistor.

16. The capacitive touch panel as claimed in claim 15, wherein the analog to digital converter transmits the first voltage value, the second voltage value, and the current value to a device driver to calculate a second resistor value of such conductive resistor.

17. The capacitive touch panel as claimed in claim 16, wherein the value of the second resistor is calculated as:

18. The capacitive touch panel as claimed in claim 17, wherein the second resistor value is converted into a coordinate value of a contacting point by a device driver, and if I is smaller than a preset value, it means that no touching is on the touch panel.